DALY CITY -- Police scrambled to a medical office building Wednesday after hearing that a man had fired a gun inside, but by late afternoon they had not found the gunman. No one was injured.

Dispatchers received a 911 call at 1:26 p.m. from a doctor who reported seeing a man with a gun in a second-floor hallway at 1500 Southgate Ave., Daly City police Lt. David Mackriss said. The doctor told police that, moments later, as he was making his way out of the building, he heard what sounded like a gunshot.

Officers and a SWAT team responded and searched the building, but did not find the gunman, described as a man in his 60s. They later found bullet fragments, Mackriss said, confirming a gun had been fired.

"We believe it was fired in the direction of the doctor reporting the incident," Mackriss said.

There were more than 30 people in the building at the time of the incident, Mackriss said. Some were evacuated right away, while others were told to hunker down and wait for police to arrive.

Police continued to investigate late Wednesday afternoon.

"We're confident the gunman is not in the area," said Mackriss, "and we're working on leads to determine his identity and apprehend him."